vorbis_dec: Change partition_class[] to uint8_t.

When sizeof(uint_fast8_t) >= sizeof(int) there are unintended size effects.

Originally committed as revision 24716 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/vorbis_dec.c

@@ -81,7 +81,7 @@ typedef struct {
         } t0;
         struct vorbis_floor1_s {
             uint_fast8_t partitions;
-            uint_fast8_t partition_class[32];
+            uint8_t      partition_class[32];
             uint_fast8_t class_dimensions[16];
             uint_fast8_t class_subclasses[16];
             uint_fast8_t class_masterbook[16];